The goal of this research is to further our understanding of the relationship between child maltreatment and subsequent drug use during adolescence and young adulthood. A wealth of correlational evidence suggests that an increased risk of drug use may be one of the most serious consequences of child maltreatment, but broad gaps in our knowledge remain. This study will extend our understanding of the maltreatment substance use association by employing a theory-driven design, attempting to identify key intervening mechanisms, including measures of the major forms of maltreatment and the major types of substances used, and by utilizing a large, nationally representative, and longitudinal data set. The specific aims of the study are to 1) provide detailed national estimates of adolescent and young adult drug use by childhood maltreatment status; 2) describe the natural history of drug use by childhood maltreatment status; and 3) test a conceptual model of maltreatment and substance use that identifies social ties to family, school, and peers as key intervening mechanisms. The data used to address these aims come from the National Longitudinal Study of Adolescent Health (Add Health), a nationally representative, probability-based survey of adolescents in grades 7-12 first interviewed in 1995 and then re-interviewed in 1996 and 2001. Self-reported measures of neglect, physical maltreatment, sexual abuse, and social service involvement experienced prior to the 6th grade are included on the Wave III instrument, when respondents will be 18-26 years old. The addition of these retrospective maltreatment reports, when combined with the wealth of repeated measures on drug use, social relationships, and other determinants of health behaviors found in Add Health, will create a new, unique, and valuable data source for examining this topic. The results from this project should inform drug abuse prevention and intervention programs, particularly those that specifically target victims of child abuse and neglect.